update Runtime to Swift 5

Author: tonisuter

Package.swift

@@ -1,4 +1,5 @@
-// swift-tools-version:4.2
+// swift-tools-version:5.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
 

Sources/AWSLambdaSwift/Runtime.swift

@@ -30,7 +30,7 @@ public class Runtime {
             throw RuntimeError.missingEnvironmentVariables
         }
 
-        guard let periodIndex = handler.index(of: ".") else {
+        guard let periodIndex = handler.firstIndex(of: ".") else {
             throw RuntimeError.invalidHandlerName
         }
 

Sources/AWSLambdaSwift/Types.swift

@@ -1,10 +1,6 @@
 import Foundation
 
-// Remove when moving to swift 5
-enum HandlerResult {
-    case success(Data)
-    case failure(Error)
-}
+typealias HandlerResult = Result<Data, Error>
 
 protocol SyncHandler {
     func apply(inputData: Data, context: Context) throws -> Data